WC-IOM-7 • Packaged Heat Pump 49
Troubleshooting
LED 4 (Service)
“On” indicates a clogged filter.
“Off” during normal operation.
“Flashing” indicates an evaporator fan failure
Below is the complete listing of failure indication causes.
System Failure
Check the voltage between terminals 6 and 9 on J6, it should read approximately
32 VDC. If no voltage is present, a System failure has occurred. Refer to Step 4 in
the previous section for the recommended troubleshooting procedure.
Cooling Failure
1. Cooling and heating set point (slide pot) on the zone sensor has failed. Refer
to the “Zone Sensor Test Procedure” section.
2. Zone temperature thermistor ZTEMP on ZTS failed. Refer to the “Zone
Sensor Test Procedure” section.
3. CC1 or CC2 24 VAC control circuit has opened, check CC1 & CC2 coils, and
any of the controls below that apply to the unit (HPC1, HPC2).
4. LPC1 has opened during the 3 minute minimum “on time” during 4
consecutive compressor starts, check LPC1 or LPC2 by testing voltage
between the J1-8 & J3-2 terminals on the RTRM and ground. If 24 VAC is
present, the LPC’s has not tripped. If no voltage is present, LPC’s has tripped.
Service Failure
5. If the supply fan proving switch has closed, the unit will not operate (when
connected to RTOM), check the fan motor, belts, and proving switch.
6. Clogged filter switch has closed, check the filters.
Simultaneous Heat and Cool Failure
1. Emergency Stop is activated.
Method 2
The second method for determining system status is done by checking voltage
readings at the RTRM (J6). The system indication descriptions and the
approximate voltages are listed below.
System Failure
Measure the voltage between terminals J6-9 & J6-6.
Normal Operation = approximately 32 VDC
System Failure = less than 1 VDC, approximately 0.75 VDC
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